A well-known editor at news giant Reuters has been indicted by a federal grand jury on felony charges of conspiring with a notorious hacker group to deface the website of The Los Angeles Times in 2010 after he had been “terminated” by the paper’s parent company. Reuters deputy social media editor Matthew Keys, 26, allegedly provided the Anonymous hacking collective with login credentials for a Tribune Co. server, allowing one of the group’s hackers to access the LA Times website and alter a news report.

Keys’ indictment, which stunned the media world Thursday, is just the latest example of the federal government’s aggressive campaign to crack down on electronic hacking. Keys is currently deputy social media editor at Reuters, where he uses Twitter and other digital tools to promote Reuters stories and cover breaking news events. He is a well-known presence on Twitter, and in 2012, he was included on TIME’s list of the 140 Best Twitter Feeds.

Keys was charged with three felonies: Conspiracy to transmit information to damage a protected computer, transmitting information to damage a protected computer, and attempted transmission of information to damage a protected computer, according to the federal indictment released Thursday. The conspiracy count carries a maximum penalty of five years in prison, three years of supervised release and a fine of $250,000, according to prosecutors. The other two counts each carry a maximum penalty of 10 years in prison, three years of supervised release and a fine of $250,000.

Keys did not respond to multiple requests for comment, but in a post on his widely read Twitter account, which has nearly 24,000 followers, he wrote: “I am fine. I found out the same way most of you did: From Twitter. Tonight I’m going to take a break. Tomorrow, business as usual.” Reuters did not comment on Keys’ employment status, but in a news account of the indictment, Reuters reported that Keys’ computer was being dismantled and his security pass had been deactivated, according to a Reuters employee at the New York City office where Keys worked.

The federal charges relate to events that occurred before Keys joined Reuters, after he had been “terminated” as a web producer for Tribune-owned, Sacramento-based television station KTXL FOX 40. Tribune owns the LA Times. Anonymous is a well-known, loosely affiliated group of computer hackers who have claimed responsibility for attacks on numerous companies, including Visa, Mastercard, PayPal and Amazon.com.

In a statement, Reuters, which is the news-gathering arm of media and information giant Thomson Reuters, said it was aware of the indictment against Keys. “Any legal violations, or failures to comply with the company’s own strict set of principles and standards, can result in disciplinary action,” the company said. “We would also observe the indictment alleges the conduct occurred in December 2010; Mr. Keys joined Reuters in 2012, and while investigations continue we will have no further comment.”

According to the indictment, federal prosecutors allege that in December 2010 Keys provided members of Anonymous with login and password information for a Tribune computer server. Keys then allegedly encouraged the hackers to “go f— some s— up,” according to the indictment. At least one of the hackers allegedly proceeded to access the Tribune server using the credentials Keys provided and make changes to a news story on the LA Times website.

The LA Times news article had originally been headlined: “Pressure Builds in House to Pass Tax-Cut Package.” But the story was renamed to read “Pressure Builds in the House to Elect CHIPPY 1337,” with the byline reading, “By CHIPPYS NO1 FAN,” according to the indictment. When the hacker allegedly informed Keys that the story had been changed, Keys responded, “nice.”

This is not the first time Keys’ name has been brought up in conjunction with Anonymous. In 2011, someone named “Sabu” tweeted that Keys had given “full control of LATimes.com to hackers.” Sabu was later revealed to be Anonymous leader Hector Xavier Monsegur, who was arrested by the FBI on June 7, 2011. According to multiple reports, Monsegur acted as an FBI informant before his arrest, and has been providing information to the federal government ever since.

“Since literally the day he was arrested, [Monsegur] has been cooperating with the government proactively,” Assistant U.S. Attorney James Pastore said at a secret bail hearing on Aug. 5, 2011, according court papers cited by The Wall Street Journal. Monsegur was supposed to be sentenced last month, but his hearing was delayed for unknown reasons.

In an interview with Reuters, Benjamin Wagner, U.S. Attorney for the Eastern District of California, suggested that Keys was acting as a disgruntled former Tribune employee. He had previously been “terminated” from his job at Tribune-owned TV news station KTXL FOX 40. In the Reuters interview, Wagner said that because Keys was a journalist, the case was taken to high-level Justice Dept. officials for approval, “out of an abundance of caution.”

According to the indictment, the case was investigated by the Sacramento and Los Angeles Field Offices of the FBI, and is being prosecuted by the Criminal Division’s Computer Crime and Intellectual Property Section and the U.S. Attorney’s Office for the Eastern District of California. Keys is scheduled to be arraigned April 12.